Hub assembly for a tire inflation system

ABSTRACT

A hub assembly for a tire inflation system includes a hub configured to hold a wheel assembly. The hub has a hub conduit formed therethrough. The hub conduit has an inlet formed in an inner surface of the hub and an outlet formed adjacent an outboard end of the hub. A vent is formed in the hub. The vent includes one or more vent conduits which extend from the inner surface to an outer surface of the hub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of the non-provisionalapplication granted Ser. No. 13/261,968, which was filed on Oct. 8, 2014and is now U.S. Pat No. 9,446,637, the entire disclosure of which ishereby incorporated by reference, which is a national stage applicationof the international application granted Serial No. PCT/US2013/035588filed on Apr. 8, 2013, which claims the benefit of the provisionalapplications granted Ser. Nos. 61/621,601 filed on Apr. 9, 2012,61/653,482 filed on May 31, 2012, and 61/790,349 filed on Mar. 15, 2013,the entire disclosures of which are hereby incorporated by reference.This application is also claiming the benefit, under 35 U.S.C. 119(e),of the provisional application granted Ser. No. 62/333,535 filed on May9, 2016, the entire disclosure of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The invention relates to a tire inflation system for a vehicle. Moreparticularly, the invention relates to a tire inflation system whichutilizes a conduit formed through a hub to communicate a pressurizedfluid, such as air, to one or more tires provided on a drive axle of thevehicle.

Tire inflation systems for vehicles are used to provide a vehicle withthe versatility to maneuver over differing terrain types and to reducemaintenance requirements. For example, a plurality of tires in fluidcommunication with a tire inflation system may be at a pressure whichcan be lowered to provide additional traction for the vehicle or raisedto reduce the rolling resistance and increase the fuel efficiency of thevehicle. Additionally, utilizing a tire inflation system may eliminatethe need to periodically check and adjust the pressure within each tire.However, tire inflation systems are difficult to install on a drive axledue to the increased complexities associated therewith, spacingrequirements, and associated costs.

Thus, it would be desirable to provide a tire inflation system thatincludes one or more of the aforementioned advantages and overcomes theaforementioned difficulties.

BRIEF SUMMARY OF THE INVENTION

A hub assembly for a tire inflation system is provided. In anembodiment, the hub assembly comprises a hub configured to hold a wheelassembly. The hub has a hub conduit formed therethrough. The hub conduithas an inlet formed in an inner surface of the hub and an outlet formedadjacent an outboard end of the hub. A vent is formed in the hub. Thevent comprises one or more vent conduits which extend from the innersurface to an outer surface of the hub.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The above, as well as other advantages of the process will becomereadily apparent to those skilled in the art from the following detaileddescription when considered in the light of the accompanying drawings inwhich:

FIG. 1 depicts a front view of a drive axle assembly which has a tireinflation system in accordance with the invention;

FIG. 2 depicts an end view of the drive axle assembly of FIG. 1;

FIG. 3 depicts a cross-sectional view of a portion of the drive axle ofFIG. 1 along line 3-3 and illustrates an embodiment of the tireinflation system in accordance with the invention;

FIG. 4 depicts a cross-sectional view of a portion of the drive axle ofFIG. 1 along line 4-4 and illustrates another embodiment of the tireinflation system in accordance with the invention;

FIG. 5 depicts a cross-sectional view of a portion of the drive axle ofFIG. 1 along line 5-5 with portions of the hub removed for the ease ofdepiction and illustrates a further embodiment of the tire inflationsystem in accordance with the invention;

FIG. 6 depicts a perspective view of an embodiment of a sealing ringsuitable for use in the various embodiments of the tire inflationsystem;

FIG. 7 depicts a plan view of the sealing ring of FIG. 6;

FIG. 8 depicts a cross-sectional view of the sealing ring taken alongline 8-8;

FIG. 9 depicts a cross-sectional view of a portion of an embodiment ofan outer rotary seal for use in the various embodiments of the tireinflation system;

FIG. 10 depicts a cross-sectional view of a portion of an embodiment ofan inner rotary seal for use in the various embodiments of the tireinflation system;

FIG. 11 depicts an enlarged view of a portion of the tire inflationsystem shown in FIG. 3 having portions of the system removed for theease of illustration;

FIG. 12 depicts a perspective view of an embodiment of a tone ringsuitable for use in the various embodiments of the tire inflationsystem;

FIG. 13 depicts a partial sectional view of an embodiment of the hubassembly in accordance with the invention;

FIG. 14 depicts a partial sectional view of an embodiment of a hubsuitable for use in the various embodiments of the hub assembly;

FIG. 15 depicts a partial sectional view of an embodiment of a wheel endassembly including a portion of the hub assembly of FIG. 13; and

FIG. 16 depicts a partial sectional view of another embodiment of a hubassembly in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices,assemblies, systems and processes illustrated in the attached drawings,and described in the following specification are simply exemplaryembodiments of the inventive concepts defined in the appended claims.Hence, specific dimensions, directions or other physical characteristicsrelating to the embodiments disclosed are not to be considered aslimiting, unless the claims expressly state otherwise.

Embodiments of a tire inflation system 20 are described herein. The tireinflation system will be described in connection for use with a vehicle(not depicted). It would be understood by one of ordinary skill in theart that the various embodiments of the tire inflation system describedherein may have applications to commercial and off-highway vehicles.Furthermore, it would be understood by one of ordinary skill in the artthat these embodiments could have industrial, locomotive, military andaerospace applications.

Embodiments of the tire inflation system 20, which hereinafter may alsobe referred to as the “system”, are preferably used with a drive axleassembly 22 for the vehicle. An embodiment of the drive axle assembly 22suitable for use with the tire inflation system 20 is best shown inFIGS. 1 and 2. However, it should be appreciated that the tire inflationsystem may be used apart from a drive axle assembly. For example, incertain embodiments (not depicted), the tire inflation system may beused with a steer axle assembly.

As illustrated in best in FIGS. 3-5, the tire inflation system 20comprises an axle housing 24. The axle housing 24 may be formedunitarily or may comprise a plurality of components coupled together.The axle housing 24 is a hollow member into which an axle 26 isrotatably disposed through. In an embodiment, the axle housing 24comprises an outer surface 28 which is of a stepped cylindrical shapeand may reduce in diameter towards an end 30.

The axle 26 is rotatably disposed in the axle housing 24 and ispreferably a drive axle. The axle 26 includes a flanged end 32. Theflanged end 32 has a plurality of perforations 34 formed therethroughfor coupling the axle 26 to a hub assembly 36. Preferably, the axle 26is coupled to the hub assembly 36 with a plurality of threaded fasteners38. However, it should be understood that the axle 26 may be coupled tothe hub assembly 36 in any other conventional manner.

The tire inflation system 20 comprises a sealing ring 40. The sealingring 40 and the hub assembly 36 are fitted to the axle housing 24. Thesealing ring 40 and the hub assembly 36 are disposed about the outersurface 28 of the axle housing 24. Preferably, the sealing ring 40 isnon-rotatably disposed on the outer surface 28 of the axle housing 24.

As illustrated in FIGS. 6-8, the sealing ring 40 is an annular memberand is preferably metallic. The sealing ring 40 has an outer surface 42and a conduit 44 formed therethrough. An inlet 46 of the conduit 44 isformed on an inboard edge 48 of the sealing ring 40. Preferably, theinlet is in fluid communication with a pump conduit 50 which is incommunication with a fluid pump (not depicted). As illustrated in FIG.3, the pump conduit 50 may extend around a portion of the outer surface28 of the axle housing 24. Referring to FIG. 5, an outlet 52 of theconduit 44 is formed on the outer surface 42 of the sealing ring 40.

Referring back to FIGS. 7 and 8, the outer surface 42 of the sealingring 40 is of a general cylindrical shape. The outer surface 42 maycomprise a first diameter portion 54 and a second diameter portion 56.The first diameter portion 54 has a diameter which is of a length thatis greater than that of the second diameter portion 56. The outersurface 42 may also comprise a chamfered portion 58 attached to anoutboard end 60 of the sealing ring 40. On an opposite end 62, a plate64 is attached to the inboard edge 48 of the sealing ring 40. The plate64 is utilized to hold an anti-lock brake sensor 66.

The sealing ring 40 also comprises an inner surface 68. The innersurface 68 comprises a first diameter portion 70 and a second diameterportion 72. The first diameter portion 70 has a diameter which is of alength that is greater than that of the second diameter portion 72.

The hub assembly 36 comprises a hub 74. The hub 74 is rotatably disposedon the axle housing 24. Referring back to FIG. 3, the hub 74 ispreferably rotatably disposed on the axle housing 24 using bearings 76disposed between the hub 74 and the axle housing 24. Preferably, thebearings 76 are disposed about and engaged on the axle housing 24 beforean inner rotary seal 78 and an outer rotary seal 80 are advanced duringthe manufacture of the system 20. Operating in this manner preventsmisalignment of the seals 78, 80 on the sealing ring 40 during assembly.

The hub assembly 18 may be configured to hold a wheel assembly (notdepicted) which is coupled to the hub 74 using a plurality of wheelstuds 82. The hub 74 is also attached to the axle 26 as mentionedhereinabove and drivingly engaged therewith. The hub 74 is an annularmember having an inner surface 84, an outer surface 86, and a conduit88, 88A formed therethrough.

As shown in FIG. 3, at least a portion of the inner surface 84 of thehub 74 has a stepped cylindrical shape. In this embodiment and as shownbest in FIG. 5, the inner surface 84 comprises one or more recesses 90,92. The outer surface 86 defines a hub flange 94. The hub flange 94engages the wheel assembly and brake drum and is an annular protuberancehaving a plurality of perforations formed therethrough into which wheelstuds 98 are disposed.

The conduit 88, 88A is formed through the hub 26. The hub conduit 88,88A includes an inlet 104 formed adjacent an inboard end 106 of the hub74. The inlet 104 of the hub conduit 88, 88A is formed adjacent theinner rotary seal 78 and the outer rotary seal 80. Preferably, the inlet104 is formed in the inner surface 84 of the hub 74 between the innerrotary seal 78 and the outer rotary seal 80. An outlet 108 of the hubconduit 88, 88A is formed adjacent the outboard end 110 of the hub 74.As shown, in an embodiment, an outlet portion of the hub conduit 88, 88Aadjacent the outlet 108 has an increased diameter with respect to aremaining portion of the hub conduit 88, 88A and, preferably, hasthreads formed therein for receiving a fastener 112, 112A such as, forexample, an axle bolt 112 or an axle stud 112A.

Referring now to FIG. 13, in an embodiment, the hub conduit 88A hasthree separate portions 160, 162, 164 and each portion is of a differentdiameter. In this embodiment, the hub conduit 88A includes an inletportion160 formed adjacent the inboard end 161 of the hub assembly 36.The inlet portion160 is in fluid communication with an area 120 betweenthe inner rotary seal 78 and the outer rotary seal 80. In an embodimentlike the one illustrated in FIG. 13, the inlet portion 160 is in fluidcommunication with the area 120 via a slot 166. In this embodiment, theslot 166 may be of a hemispherical shape. In another embodiment like theone illustrated in FIG. 14, the inlet portion 160 is in fluidcommunication with the area 120 via an annular groove 168 formed in theinner surface 84 of the hub 74. In this embodiment, the annular groove168 is positioned circumferentially about the area 120 and axiallybetween the outer rotary seal 80 and a shoulder 170. Referring back toFIG. 13, the outlet portion 164 of the hub conduit 88A is formedadjacent the outboard end 110 of the hub 74. As described above, theoutlet portion 164 has threads formed therein, which engaging fastenerthreads. The outlet portion 164 of the hub conduit 88A has an increaseddiameter with respect to the inlet portion 160 of the hub conduit 88A.The outlet portion 164 of the hub conduit 88A is in fluid communicationwith the inlet portion 160 of the hub conduit 88A via a middle portion162 of the hub conduit 88A. The middle portion 162 of the hub conduit88A has an increased diameter with respect to the inlet portion 160 ofthe hub conduit 88A. However, the middle portion 162 of the hub conduit88A has a diameter which is less than a diameter of the outlet portion164 of the hub conduit 88A. Advantageously, this embodiment allows for agreater wall thickness in certain portions of the hub 74 which increasesthe durability of the hub.

A bearing seal 114 is disposed between the hub 74 and the axle housing24. The bearing seal 114 may be formed from a rubber material and mayinclude at least one reinforcing member provided therein. The bearingseal 114 militates against lubricant used with the bearings 76 fromcontacting the sealing ring 40, inner rotary seal 78, and outer rotaryseal 80.

Preferably, the bearing seal 114 is disposed at a location inboard fromthe bearings 76 and outboard of the outer rotary seal 80. The bearingseal 114 is disposed on one of the axle housing 24 and the hub 74 and isin sealing contact with the remaining one of the axle housing 24 and thehub 74. In an embodiment, the bearing seal 114 is attached to the innersurface 84 of the hub 74 and is provided in a first annular recess 172defined thereby. In this embodiment, the bearing seal 114 rotates withthe hub 74 and a sealing edge 116 of the bearing seal 114 is in sealingcontact with the outer surface 28 of the axle housing 24.

Preferably, the inner rotary seal 78 is disposed between the sealingring 40 and the hub 74. As illustrated in FIG. 10, the inner rotary seal78 may be formed from a rubber material and includes at least onereinforcing member 118 provided therein. The inner rotary seal 78militates against a pressurized fluid, such as air, used in the tireinflation system 20 from exiting the area 120 between the inner rotaryseal 78 and the outer rotary seal 80.

Referring back to FIG. 3, the inner rotary seal 78 is disposed at alocation inboard from the outer rotary seal 80 and outboard from a tonering 122. Preferably, the hub 74 comprises the shoulder 170. In anembodiment, like the one illustrated in FIG. 13, the slot 166 is formedin the shoulder 170. In another embodiment, like the one illustrated inFIG. 14, the shoulder 170 is annular. In this embodiment, the shoulder170 is provided inboard of the annular groove 168. As is shown in FIG.15, the inner rotary seal 78 is provided inboard of the shoulder 170. Anoutboard end of the inner rotary seal 78 abuts the shoulder 170 and aninboard end of the inner rotary seal 78 abuts the tone ring 122. In thisembodiment, the shoulder 170 acts as a positive stop for the innerrotary seal 78 when the tire inflation system 20 is being manufactured.

The inner rotary seal 78 is disposed on one of the sealing ring 40 andthe hub 74 and is in sealing contact with the remaining one of thesealing ring 40 and the hub 74. In an embodiment, the inner rotary seal78 is attached to the inner surface 84 of the hub 74. In thisembodiment, the inner rotary seal 78 rotates with the hub 74 and asealing edge 124 of the inner rotary seal 78 is in sealing contact withthe outer surface 42 of the sealing ring 40. As best shown in FIG. 10,the inner rotary seal 78 also comprises a lip portion 126. The lipportion 126 contacts the outer surface 42 of the sealing ring 40 tomilitate against dirt and/or other debris from getting past.

Referring back to FIG. 3, preferably, the outer rotary seal 80 isdisposed between the hub 74 and the sealing ring 40. As illustrated inFIG. 9, the outer rotary seal 80 may be formed from a rubber materialand includes at least one reinforcing member 128 provided therein. Theouter rotary seal 80 militates against a pressurized fluid, such as air,used in the tire inflation system 20 from entering the area between thehub 74 and the axle housing 24 and exiting the area between the innerrotary seal 78 and the outer rotary seal 80.

As illustrated in FIG. 3, the outer rotary seal 80 is disposed at alocation inboard from the bearing seal 114 and outboard from the innerrotary seal 78. The outer rotary seal 80 is disposed on one of thesealing ring 40 and the hub 74 and is in sealing contact with theremaining one of the sealing ring 40 and the hub 74. In an embodiment,the outer rotary seal 80 is attached to the inner surface 84 of the hub74. In this embodiment, the outer rotary seal 80 rotates with the hub 74and a sealing edge 130 of the outer rotary seal 80 is in sealing contactwith the outer surface 42 of the sealing ring 40.

Preferably, the inner rotary seal 78 and the outer rotary seal 80 arespaced apart from one another and disposed about the outer surface 42 ofthe sealing ring 40. The hub conduit 88, 88A is in fluid communicationwith the conduit 44 formed through the sealing ring 40 through the area120 between the inner rotary seal 78 and the outer rotary seal 80. In anembodiment, the inner rotary seal 78 is disposed about the firstdiameter portion 54 and the outer rotary seal 80 is disposed about thesecond diameter portion 56 of the sealing ring 40. As the first diameterportion 54 is of a diameter which is greater than that of the seconddiameter portion 56, the inner rotary seal 78 is preferably of adiameter which is of a length that is greater than that of a diameter ofthe outer rotary seal 80. For example, in this embodiment, an innerdiameter of the inner rotary seal 78 is greater than an inner diameterof the outer rotary seal 80. Additionally, the inner rotary seal 78 andthe outer rotary seal 80 may be disposed in separate annular recesses90, 92 formed in the inner surface 84 of the hub 74.

The first recess 172 is positioned outboard of the second recess 92 andis spaced apart axially from second recess 92 and the third recess 90.Likewise, the second recess 92 is positioned outboard of and is spacedapart axially from the third recess 90. The second recess 92 is providedbetween and separates the first recess 172 and the third recess 90. Thethird recess 90 is the inboard most recess of the first, second, andthird recesses. In the embodiments illustrated in FIGS. 13-15, theshoulder 170 defines an outboard end of the third recess 90. Theremaining portion of the recess 90 is defined by an elongated portion174 of the inner surface 84 of the hub 74. The elongated portion 174 ofthe inner surface 84 of the hub 74 is of an annular shape and attachedto the inboard end 106 of the hub 74.

The shoulder 170 comprises an inner diameter 176 which is less than aninner diameter 178 of the third recess 90. The inner diameter 176 of theshoulder 170 is greater than an inner diameter 180 of the second recess92. Thus, the inner diameter 178 of the third recess 90 is greater thanthe inner diameter 180 of the second recess 92. The inner diameter 180of the second recess 92 is greater than an inner diameter 182 of thefirst recess 172. Thus, the inner diameter 178 of the third recess 90 isgreater than the inner diameter 182 of the first recess 172.

A space 132 is provided between the bearing seal 114 and the outerrotary seal 80. The space 132 is at least partially defined by the innersurface 84 of the hub 74. In an embodiment, like the one illustrated inFIGS. 13-14, the space 132 is defined by a groove 184 formed in theinner surface 84 of the hub 74. The groove 184 is spaced apart axiallyfrom the first recess 172 and the second recess 92. More particularly,the groove 184 is positioned outboard of the second recess 92 andinboard of the first recess 172. Preferably, the groove 184 is annular.The groove 184 may be formed in the inner surface 84 of the hub 74 byremoving a portion of the hub 74.

As shown in FIG. 5, a vent 134 may be provided in the hub 74. The vent134 is in fluid communication with space 132. When the groove 184 isformed in the inner surface 84 of the hub 74, the vent 134 is in fluidcommunication with the space 132 via the groove 184. The vent 134 isprovided to allow air which passes by the outer rotary seal 80 andlubricant which passes by the bearing seal 114 to be removed from thespace 132. Removing air and lubricant from the space 132 helps toprevent lubricant from entering the hub conduit 88, 88A and sealing ringconduit 44 and air from entering the axle housing 24.

The vent 134 is circumferentially spaced apart from the hub conduit 88,88A and positioned axially between the bearing seal 114 and the outerrotary seal 80. Thus, the vent 134 is positioned axially between thefirst recess 172 and the second recess 92 and outboard of the secondrecess 90, the third recess 92, and the shoulder 170. The vent 134 maycomprise one or more conduits 136. Preferably, as is illustrated in FIG.16, the vent 134 comprises at least three conduits 136. The one or morevent conduits 136 are formed in the hub 74 and extend from the innersurface 84 to the outer surface 86 thereof. Each conduit 136 iscircumferentially spaced apart from the hub conduit 88, 88A and is influid communication with the space 132 on an end 138 and with theatmosphere on an opposite end 140.

As shown, in an embodiment, the one or more vent conduits 136 may beoriented in a perpendicular relationship with the axle housing 24 andone or more portions of the inner surface 84 of the hub 74. However, inother embodiments (not depicted), the one or more vent conduits 136 arenot limited to being oriented in a perpendicular relationship with theaxle housing 24, the inner surface 84 of the hub 74, and/or the outersurface 86 of the hub 74. For example, in an embodiment (not depicted),the one or more vent conduits 136 are oriented in an obliquerelationship with the axle housing 24. In certain embodiments, like theone illustrated in FIG. 16, an outer portion of one or more of the oneor more vent conduits 136 is formed having threads. Preferably, thethreads are utilized to attach a vent filter 186 within the vent conduit136. The vent filter 186 prevents dirt and debris from entering the hub74. As illustrated, the vent filter 186 has threads which engage thethreads on the outer portion of the vent conduit 136.

Referring now to FIGS. 3 and 4, the fastener 112, 112A is engaged withthe hub 74 and is hollow having a conduit 142, 142A formed therethrough. The fastener conduit 142, 142A is in fluid communication withthe conduit 88, 88A formed in the hub 74. The fastener 112, 112A isdisposed through the flanged end 32 of the axle 26 such it is sealinglyengaged with the outlet 108 or outlet portion 164 of the hub conduit 88,88A. The fastener conduit 142, 142A facilitates fluid communicationbetween the hub conduit 88, 88A and a hose assembly (not shown).

In an embodiment which is shown in FIG. 3, the fastener is an axle bolt112. In this embodiment, a head portion 144 of the axle bolt 112 abutsthe flanged end 32 of the axle 26. The head portion 144 may have ahexagonal cross-sectional shape. The axle bolt 112 has the conduit 142formed therethrough and an outer surface 146 which has a thread 148formed thereon. The thread 148 formed in the outer surface 146 of theaxle bolt 112 engages the threads formed in the outlet portion 164 ofthe hub conduit 88, 88A adjacent the outboard end 110 of the hub 74. Arecess 150 having a thread formed thereon is formed in the head portion144 of the axle bolt 112.

In another embodiment which is shown in FIG. 4, the fastener is an axlestud 112A. A head portion 144A of the axle stud 112A abuts the flangedend 32 of the axle 26. The head portion 144A may have a cylindricalcross-sectional shape. The axle stud 112A has the conduit 142A formedthere through and an outer surface 146A having a thread 148A formedthereon. The thread 148A formed in the outer surface 146A of the axlestud 112A engages the threads formed in the outlet portion 164 of thehub conduit 88, 88A adjacent the outboard end 110 of the hub 74.

In certain embodiments, the tire inflation system 20 comprises the tonering 122. Tone rings are well known in anti-lock braking systems.Utilizing the anti-lock braking sensor 66 provided inboard of the tonering 122, a vehicle speed and/or a rotational rate can be determined. Anexemplary tone ring 122 suitable for use in the tire inflation system 20is illustrated in FIG. 12. As illustrated, the tone ring 122 maycomprise a plurality of apertures 152 and be generally ring-shaped. Inthis embodiment, the tone ring 122 comprises an inner diameter 154 whichdefines a major aperture 156 and an outer diameter 158.

As shown in FIGS. 3, 4, and 5, the tone ring 122 is attached to theouter surface 86 of the hub 74 at the inboard end 106 thereof.Preferably, the tone ring 122 is press-fit onto the hub 74 and isprovided inboard of the inner rotary seal 78 and the outer rotary seal80. In an embodiment, the tone ring 122 abuts the inner rotary seal 78and the inboard end 106 of the hub 74. In this embodiment, the tone ring122 prevents the inner rotary seal 78 from moving axially inboard of thefirst diameter portion 54 of the outer surface 42 of the seal ring 40.

The hose assembly comprises a fitting (not depicted), a hose (notdepicted), and a valve fitting (not depicted). The valve fitting issealingly engaged with the fastener 112, 112A. The valve fitting is influid communication with the fastener 112, 112A via a conduit (notdepicted) formed through the hose and the fitting. The valve fitting issealingly engaged with a tire valve (not depicted).

In use, the tire inflation system 20 facilitates fluid communicationbetween the sealing ring conduit 44 and the hose assembly. When a fluidis pumped into or a pressure is applied to the sealing ring conduit 44,the fluid travels through or the pressure is applied to the area 120between the inner rotary seal 78 and the outer rotary seal 80, the hubconduit 88, 88A, the fastener conduit 142, 142A and the hose assembly.

The pump (not depicted) is capable of pumping the fluid into or applyinga pressure to the hub conduit 88, 88A and is activated by a controller(not depicted) in response to a pressure within a tire (not depicted) asdetermined by a pressure sensor (not depicted) in communication with thecontroller. Alternately, the pump may be activated manually by anoperator of the vehicle that the tire inflation system 20 isincorporated in, at periodic intervals to ensure each of the tires ismaintained at a desired pressure, in response to changes in ambienttemperature, or in response to changes in terrain.

In accordance with the provisions of the patent statutes, the presentinvention has been described in what is considered to represent itspreferred embodiments. However, it should be noted that the inventioncan be practiced otherwise than as specifically illustrated anddescribed without departing from its spirit or scope.

What is claimed is:
 1. A hub assembly for a tire inflation system,comprising: a hub configured to hold a wheel assembly, wherein the hubhas a hub conduit formed therethrough and the hub conduit has an inletand an outlet; and a vent formed in the hub, wherein the vent comprisesone or more vent conduits which extend from an inner surface to an outersurface of the hub.
 2. The hub assembly of claim 1, wherein the inlet isformed in an inner surface of the hub and the outlet is formed adjacentan outboard end of the hub, the inlet being formed adjacent an inboardend of the hub and the hub conduit extending axially toward the outboardend of the hub to the outlet.
 3. The hub assembly of claim 1, whereinthe one or more vent conduits are positioned axially between separaterecesses formed in the inner surface of the hub.
 4. The hub assembly ofclaim 1, wherein the vent is circumferentially spaced apart from the hubconduit.
 5. The hub assembly of claim 1, wherein the one or more ventconduits are oriented in a perpendicular relationship with the innersurface of the hub.
 6. The hub assembly of claim 1, wherein the one ormore vent conduits are oriented in a perpendicular relationship with anouter surface of the hub.
 7. The tire inflation system of claim 1,wherein a portion of the hub conduit adjacent the outlet has anincreased diameter with respect to a remaining portion of the hubconduit.
 8. The hub assembly of claim 1, wherein separate recesses areformed in the inner surface of the hub.
 9. The hub assembly of claim 1,wherein the hub conduit is in fluid communication with a conduit formedthrough a fastener engaged with the hub.
 10. The hub assembly of claim1, further comprising a tone ring attached to the outer surface of thehub at an inboard end thereof.
 11. The hub assembly of claim 1, whereinthe inner surface of the hub comprises a first recess axially spacedapart from a second recess and the vent is positioned between therecesses and outboard of a shoulder.
 12. The hub assembly of claim 4,wherein the one or more vent conduits which are each circumferentiallyspaced apart from the hub conduit.
 13. The hub assembly of claim 7,wherein the increased diameter portion of the hub conduit has threadsformed therein.
 14. The hub assembly of claim 8, wherein the separaterecesses are axially spaced apart along the inner surface of the hub.15. The hub assembly of claim 10, wherein the tone ring is press fit tothe inboard end of the hub.
 16. The hub assembly of claim 11, whereinthe inner surface of the hub further comprises a third recess axiallyspaced apart from the second recess, the third recess being at leastpartially defined by the shoulder.
 17. The hub assembly of claim 11,wherein the first recess defines a first inner diameter and the secondrecess defines a second inner diameter, the second inner diameter beinggreater than the first inner diameter.
 18. The hub assembly of claim 16,wherein the third recess is separated from the first recess by thesecond recess and the first recess is provided axially outboard of thesecond recess.
 19. The hub assembly of claim 17, wherein the innersurface of the hub further comprises a third recess axially spaced apartfrom the second recess, the third recess defining a third inner diameterand the third inner diameter being greater than the second innerdiameter.
 20. A drive axle assembly comprising the hub assembly of claim1.